The ability to determine the location of persons or devices in an indoor environment has become increasingly important for many applications. With the wide adoption of global satellite positioning systems, outdoor positioning has become very reliable. Many applications, however, also require or could benefit from seamless localization capabilities in indoor environments. Therefore, indoor localization has become a focus of research and development during the past decade. Improvements in localization performance will create unprecedented opportunities for many online and offline businesses. Applications include navigating users to a particular store (or other room) in a mall or to an office (or other room) in a public building. In particular, location-based advertisements and location-based search services are expected to be commercially valuable.
Known techniques for indoor localization operate to locate objects inside a building using radio waves, acoustic signals, or other sensory information collected by mobile nodes. The ability to provide precise location/navigation services for customers in commercial buildings such as shopping malls, department stores, and hospitals is directly linked to revenues. Real-time data on the location of consumers is very valuable to many parties, including stores, and third party applications compete for the users' attention and for ownership of data on consumer movements and habits. The data can provide information on how customers navigate stores and go about making their purchasing decisions.
While various methods have been proposed for indoor localization, no solution has gained universal approval. For the physical localization of a mobile node in buildings, proposed methods involve techniques such as, for example, geometric trilateration using radio signals from Wi-Fi access points or location fingerprinting using a pre-established map of environmental signals (such as magnetic fields, Wi-Fi signals, etc.). One notable recent approach is the “iBeacon” infrastructure promoted by Apple Inc. Beacons can employ the BLE (Bluetooth Low Energy) standard using low-powered, low-cost transmitters that can notify nearby mobile devices of their presence. Such systems enable a mobile node to determine that it is in proximity to a beacon device, but they do not necessarily provide the physical localizations of the mobile node in a building. Without extensive setup, beacons do not offer a pinned location like GPS. Beacons thus generally act as an indoor proximity solution, not an indoor localization solution. Beacons are increasingly deployed in many commercial buildings such as shopping malls, department stores, and mega complex buildings.
The use of beacon-type devices for further physical localization of mobile nodes indoors requires a “site survey.” For example, a site survey may be performed to build a database of radio frequency fingerprints by measuring beacon signals in each position in a building and mapping the indoor locations in advance. If a trilateration method is to be used, for indoor localization, the exact location of beacon devices in each building or store is provided to mobile nodes.